Radio communication systems are known which support communication among several users operating in a wireless environment over radio frequencies. The frequencies used by these systems are a subset of the radio frequency spectrum, which are organized into one or more radio communication channels such as frequency channels. In such a system, for example, a communication link may be established between groups of communication devices within the radio system. The communication link is established over one or more frequency channels for the duration of the communication. Generally, the frequency spectrum available for a given radio system is a limited communication resource and several users may be competing for this resource. Thus, a radio communication system typically employs a frequency management methodology in order to maximize the efficient use of the available frequencies, and to minimize interference among users. This approach is useful where multiple communication links must be established over shared communication channels.
Many frequencies sharing methodologies are known in the art. Examples include channel hopping, direct sequence spread spectrum, time division multiplex, and other similar schemes. Most prior art frequency sharing methods employ an infrastructure to manage the operational aspects of the radio communication system. An infrastructure typically includes a base station, or some other type of controller, which manages frequency assignments, user access, collision detection and resolution, and other operational aspects of the radio system. These controllers tends to represent a significant cost in the establishment of a radio communication system.
Low cost radio communication systems are becoming an increasingly important segment of the wireless communication market. These low cost systems must also successfully manage the use of shared frequencies in order to maximize efficiency and throughput. Some low cost systems involve self-organizing communication units which employ frequency management methodologies that do not require the use of a central controller. However, without a central controller, frequency management issues such as channel use allocation become more difficult. For example, a particular communication link may be operated in simplex transmission mode which require a particular transmission bandwidth. Another communication link may be established in which transmissions are in duplex mode requiring substantially more transmission bandwidth. Yet another communication link may be established in which data transmission requires a large allocation of transmission bandwidth. Such flexibility in allocation of transmission bandwidth is generally unavailable in low cost, infrastructureless, radio communication systems employing frequency hopping protocols. It is desirable to provide a system which accommodates different transmission bandwidth needs while providing for a low cost infrastructureless system.